Methods for removing particles from etching chamber
A method includes forming a coating layer in a dry etching chamber, placing a wafer into the dry etching chamber, etching a metal-containing layer of the wafer, and moving the wafer out of the dry etching chamber. After the wafer is moved out of the dry etching chamber, the coating layer is removed.
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This application is a divisional of U.S. patent application Ser. No. 14/273,827, entitled “Methods for Removing Particles from Etching Chamber,” filed on May 9, 2014, now U.S. Pat. No. 9,355,823, which application is incorporated herein by reference.
BACKGROUNDThe formation of integrated circuit often involves etching metal layers. For example, aluminum-containing gate electrodes and aluminum copper pads are commonly seen integrated circuit components. These components are formed by depositing a blanket metal layer, and then patterning the blanket metal layer as desirable patterns using an etching process.
The etching of the metal layer may be performed in a dry etching chamber, which is vacuumed, and etching gases are introduced into the etching chamber to etch the metal layer. In the etching process, plasma is generated from the etching gases. The metal ions in the metal layer may sometimes react with the ions in the etching gases to form particles. For example, when aluminum is etched, the aluminum ions may react with fluorine ions to form aluminum fluorine (AlF) particles, which stick to the inner surface of the etching chamber. The bonding of the AlF particles to the inner surface of the etching chamber, however, is weak. Hence, the bonds between the AlF particles and the inner surface may break, and the AlF particles fall on wafers, causing manufacturing yield to drop.
AlF has a high vaporizing temperature. Hence, it is difficult to remove the AlF particles.
Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.
A dry etching process and the corresponding particle removal process are provided in accordance with various exemplary embodiments. The intermediate stages of performing the dry etching and the particle-removal and metal clean processes are illustrated. The apparatus for the dry etching and removing the particles is also illustrated. The variations of the embodiments are discussed. Throughout the various views and illustrative embodiments, like reference numbers are used to designate like elements.
Gas-flow re-distributor 18 is mounted in chamber 12 to separate chamber 12 into a top portion over gas-flow re-distributor 18, and a bottom portion under gas-flow re-distributor 18. Gas-flow re-distributor 18 is used to force the gas overlying wafer station 16 to flow through the through-holes 20 in gas-flow re-distributor 18, so that the distribution of the gas flow is more uniform. For example, gas-flow re-distributor 18 may include a plurality of through-holes 20 aligned to a plurality of concentric rings (also refer to
In some embodiments, through-holes 20 are aligned to five (or more or fewer) concentric rings, with the corresponding through-holes 20 denoted as 20-1, 20-2, 20-3, 20-4, and 20-5, with 20-1 being the innermost through-holes, and 20-5 being the outmost through-holes. Through-holes 20 may have round top-view shapes, for example, as illustrated in
With the inner through-holes 20 having smaller sizes than the outer through-holes 20, the gas flow resistance for process gas or air flowing through the inner through-holes is greater than the gas flow resistance for the process gas or air flowing through the outer through-holes. Since pump 14 is aligned to center 22, the gas/air in the region over wafer station 16 tends to flow through the paths closer to wafer station 16 faster. Therefore, by increasing the gas flow resistance of the inner paths closer to wafer station 16, more gas/air is diverted to flow through the outer paths farther away from wafer station 16. By selecting appropriate sizes for through-holes, as described in the embodiments of the present disclose, the gas/air flow is substantially uniform, and the back-stream of the gas/air, which back-stream flows upwardly in certain regions, is eliminated. Since the back-stream may cause more metal particles that are generated by the etching of wafers (as shown in
As shown in
When coating layer 30 is to comprise SiClOx, with x being 3 or 4, the respective process gases used for forming coating layer 30 may include SiCl4 and oxygen (O2). Argon may or may not be included. SiCl4 and oxygen react to form SiClOx, wherein more oxygen results in more SiClO4 and less SiClO3, and vice versa. On the other hand, when coating layer 30 is to comprise SiOx, wherein x may be 1 or 2, the respective process gases may include SiH4 and oxygen (O2), and argon may or may not be included. SiH4 and oxygen react to form SiOx, wherein more oxygen results in more SiO2 and less SiO, and vice versa.
In the process for forming coating layer 30, the process gases are introduced into chamber 12, and are in-situ reacted. In some exemplary coating process, the pressure of the processes is in the range between about 10 mTorr and about 30 mTorr, which is considered as a high pressure because in similar deposition processes, a pressure higher than about 5 mTorr is typically considered as a high pressure. The power for the reaction may be in the range between about 500 Watts and about 1,500 Watts. The flow rate of argon may be in the range between about 10 sccm and about 50 sccm. The flow rate of SiCl4 may be in the range between about 100 sccm and about 300 sccm. The flow rate of O2 may be in the range between about 50 sccm and about 100 sccm. The reaction time may be in the range between about 10 seconds and about 20 seconds. Thickness T1 of the coating layer 30 on the top inner surface and the top parts of the sidewalls may be in the range between about 5 Å and about 50 Å.
The “high” pressure used in the coating process will reduce the mean free path and prolong gas residence time of the reaction gas, so that the radicals of the reaction gases may survive longer. As a result, coating layer 30 is mainly deposited on the upper portions (of the region over wafer station 16) of the inner surface of chamber 12, while in the lower portions (of the region over wafer station 16), the thickness of coating layer 30 is small. There may be a transition region, as illustrated, in which the thickness of coating layer 30 reduces gradually. The transition region may occur, for example, at approximately the same level as wafer 32 (
In the etching process, the residue metal ions of metal-containing layer 34, such as Al ions, may remain in chamber 12, which may be caused by the sputtering resulted from the plasma used in the metal etching process. In a subsequent process, an in-situ metal cleaning may be performed, for example, using a fluorine-containing gas (such as SF6) as a cleaning gas for removing the residue ions. In the exemplary metal cleaning process, SF6 is introduced into chamber 12. The fluorine ions react with the metal ions such as Al ions to generate metal particles. The metal particles, such as aluminum fluoride (AlF) particles, are attached to coating layer 30, as illustrated in
In some embodiments, the AlF particles may also be adhered to gas-flow re-distributor 18, which is illustrated as 36 in
Wafer 32 is then moved out of chamber 12, and the resulting etching tool 10 is illustrated in
Coating layer 30 is then removed in an in-situ etching step, and the resulting etching tool 10 is shown in
After the coating removal step as shown in
Referring to
In some embodiments of the present disclosure, coating layer 30 is removed before the metal cleaning step. In alternative embodiments, the metal cleaning step is performed before the removal of coating layer 30.
As a result of the metal clean, metal particles 36 are substantially fully removed from chamber 12, and hence the yield of the subsequent process steps will not be affected by the metal particles generated in the cycle shown in
The embodiments of the present disclosure have some advantageous features. By forming a coating layer, and then removing the coating layer after the metal etching process, the undesirable metal particles may be adhered tightly to the coating layer, so that the metal particles will not fall on the wafer. The metal particles are removed by removing the coating layer. By forming the coating layer using a relatively high pressure, the top part of the chamber is covered more thoroughly with the coating layer. Since the yield loss is mainly affected to the metal particles falling from the top part of the chamber, the problem of falling particles is eliminated effectively.
In accordance with some embodiments of the present disclosure, method includes forming a coating layer in a dry etching chamber, placing a wafer into the dry etching chamber, etching a metal-containing layer of the wafer, and moving the wafer out of the dry etching chamber. After the wafer is moved out of the dry etching chamber, the coating layer is removed.
In accordance with alternative embodiments of the present disclosure, a method includes placing a wafer into a dry etching chamber, with a gas-flow re-distributor located in the dry etching chamber. The gas-flow re-distributor includes an inner edge encircling a wafer station, with the wafer being placed on the wafer station, an outer edge concentric with the inner edge, and a plurality of through-holes between the inner edge and the outer edge. A metal-containing layer of the wafer is etched. The wafer is then moved out of the dry etching chamber. After the wafer is moved out of the dry etching chamber, an in-situ etching process is performed to remove metal particles from a surface of the gas-flow re-distributor.
In accordance with yet alternative embodiments of the present disclosure, an apparatus includes a dry etching chamber, a wafer station in the dry etching chamber; and a gas-flow re-distributor located in the dry etching chamber. The gas-flow re-distributor separates the chamber into a top portion over the gas-flow re-distributor and a bottom portion under the gas-flow re-distributor. The gas-flow re-distributor includes an inner edge encircling the wafer station, an outer edge concentric with the inner edge, and a plurality of through-holes between the inner edge and the outer edge. The plurality of through-holes connects the top portion of the dry etching chamber to the bottom portion of the dry etching chamber.
The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.
Claims
1. A method comprising:
- etching a wafer using an etching tool, wherein the etching tool comprises: a wafer station, wherein the wafer is placed on the wafer station during the etching; a dry etching chamber, with the wafer station in the dry etching chamber; and a coating layer on an inner surface of the dry etching chamber, wherein the coating layer comprises a silicon-based oxide exposed to a vacant inner space of the dry etching chamber, wherein a gas-flow re-distributor located in the dry etching chamber redistributes gas flow during the etching, and the gas-flow re-distributor separates the dry etching chamber into a top portion over the gas-flow re-distributor and a bottom portion under the gas-flow re-distributor, and the gas-flow re-distributor comprises: an inner edge encircling the wafer station; an outer edge concentric with the inner edge; and a plurality of through-holes between the inner edge and the outer edge, wherein the plurality of through-holes interconnect the top portion and the bottom portion of the dry etching chamber, and the gas-flow re-distributor comprises Y2O3 at surface.
2. The method of claim 1, wherein the coating layer comprises SiClOx, with x being three or four.
3. The method of claim 1, wherein the inner edge of the gas-flow re-distributor has a center, and first ones of the plurality of through-holes closer to the center have smaller sizes than second ones of the plurality of through-holes farther away from the center than the first ones.
4. The method of claim 3, wherein the plurality of through-holes has increasingly greater sizes with an increase in distances between the plurality of through-holes and the center.
5. The method of claim 1 further comprising:
- after the wafer is etched, moving the wafer out of the dry etching chamber; and
- removing the coating layer.
6. The method of claim 5 further comprising:
- coating an additional coating layer on the inner surface of the dry etching chamber; and
- etching an additional wafer in the dry etching chamber.
7. The method of claim 6, wherein when the additional coating layer is coated on the inner surface of the dry etching chamber, the additional coating layer is not coated on the gas-flow re-distributor.
8. The method of claim 1, wherein the gas-flow re-distributor is free from the coating layer.
9. A method comprising:
- etching a wafer using an etching tool, wherein the etching tool comprises: a dry etching chamber; a coating layer on an inner surface of the dry etching chamber, wherein the coating layer comprises SiClOx, with x being three or four; a wafer station in the dry etching chamber, wherein the wafer is placed on the wafer station; and a gas-flow re-distributor located in the dry etching chamber, wherein the gas-flow re-distributor separates the dry etching chamber into a top portion over the gas-flow re-distributor and a bottom portion under the gas-flow re-distributor, and wherein the gas-flow re-distributor comprises: an inner edge encircling the wafer station; an outer edge concentric with the inner edge; and a plurality of through-holes between the inner edge and the outer edge.
10. The method of claim 9, wherein the gas-flow re-distributor is free from the coating layer.
11. The method of claim 9, wherein a metal sputtered from the wafer during the etching is attached to the coating layer.
12. The method of claim 11, wherein the dry etching chamber further comprises a quartz layer, and the coating layer is on an inner side of, and in contact with, the quartz layer.
13. The method of claim 11 further comprising:,
- after the wafer is etched, removing the wafer from the dry etching chamber;
- etching the coating layer;
- coating an additional coating layer on the inner surface of the dry etching chamber; and
- etching an additional wafer in the dry etching chamber when the additional coating layer is present in the dry etching chamber.
14. The method of claim 13, wherein when the additional coating layer is coated on the inner surface of the dry etching chamber, the additional coating layer is not coated on the gas-flow re-distributor.
15. The method of claim 9, wherein the gas-flow re-distributor comprises Y2O3 as a surface layer.
16. A method comprising:
- performing a plurality of cycles in a dry etching chamber of an etching tool, wherein each of the plurality of cycles comprises: etching a wafer in the dry etching chamber; removing a coating layer located on an inner surface of the dry etching chamber; and re-coating an additional coating layer on the inner surface of the dry etching chamber, wherein in the re-coating, the additional coating layer is not coated on a gas-flow re-distributor located in the dry etching chamber, with the gas-flow re-distributor separating the dry etching chamber into a first portion higher than the wafer, and a second portion lower than the wafer.
17. The method of claim 16, wherein each of the coating layer and the additional coating layer comprises a silicon-based oxide.
18. The method of claim 17, wherein each of the coating layer and the additional coating layer comprises SiClOx, with x being three or four.
19. The method of claim 16, wherein during the etching, a gas-flow re-distributor located in the dry etching chamber redistributes gas flow, wherein the gas-flow re-distributor separates the dry etching chamber into a top portion over the gas-flow re-distributor and a bottom portion under the gas-flow re-distributor, and the gas-flow re-distributor comprises a plurality of through-holes interconnecting the top portion and the bottom portion of the dry etching chamber.
20. The method of claim 19, wherein the plurality of through-holes has increasingly greater sizes with an increase in distances between the plurality of through-holes and a center of the gas-flow re-distributor.
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Type: Grant
Filed: May 25, 2016
Date of Patent: Apr 3, 2018
Patent Publication Number: 20160268106
Assignee: Taiwan Semiconductor Manufacturing Company, Ltd. (Hsin-Chu)
Inventors: Yu Chao Lin (Hsin-Chu), Yuan-Ming Chiu (Taipei), Ming-Ching Chang (Hsin-Chu), Hsin-Yi Tsai (Hsin-Chu), Chao-Cheng Chen (Hsin-Chu)
Primary Examiner: Roberts Culbert
Application Number: 15/164,509
International Classification: H01L 21/311 (20060101); H01J 37/32 (20060101); H01L 21/3213 (20060101); H01L 21/67 (20060101); H01L 21/3065 (20060101);